1. Field of the Disclosure
The present disclosure relates to a semiconductor device.
2. Description of Related Art
A diode is disclosed in Japanese Patent Application Publication No. 2015-141935 (JP 2015-141935 A). Trenches are formed on an upper surface of a semiconductor substrate. An inner surface of each of the trenches is covered with an insulation layer. An electrode is disposed in each of the trenches. Each of the trenches penetrates p-type anode layer (body layer) and reaches an n-type drift layer. The p-type anode layer of this diode is vertically divided by an n-type barrier layer. The n-type drift layer is disposed below the lower anode layer. An n-type cathode layer is disposed on a lower side of the n-type drift layer.
When a forward voltage is applied to this diode, holes flow from the upper anode layer to the n-type cathode layer via the n-type barrier layer, the lower anode layer, and the n-type drift layer. Meanwhile, electrons flow in a direction opposite from the flow of the holes. When the forward voltage is applied to the diode, a p-n junction as an interface between the n-type barrier layer and the lower anode layer becomes a barrier against the holes. Accordingly, the holes are suppressed from flowing into the n-type drift layer from the upper anode layer via the n-type barrier layer and the lower anode layer. When the applied voltage to the diode is switched from the forward voltage to a reverse voltage thereafter, the holes existing in the n-type drift layer are discharged to an anode electrode via the lower anode layer, the n-type barrier layer, and the upper anode layer. A reverse current (a so-called reverse recovery current) thereby flows through the diode. With a flow of the reverse recovery current, loss (so-called reverse recovery loss) occurs to the diode. However, because the holes are suppressed from flowing into the n-type drift layer during application of the forward voltage, a small number of holes are discharged from the n-type drift layer to the anode electrode during application of the reverse voltage. Thus, the reverse recovery loss is suppressed in this diode.